Method for testing a capacity of a drive rescue battery of a transportation system, software program, and testing arrangement

1. A method of operating a testing arrangement for testing a capacity of a drive rescue battery for driving an electric motor of a transportation system in a rescue operation mode, the testing arrangement including a detector configured to measure one or more of a voltage and a current of the drive rescue battery, an AC power supply including AC mains configured to supply three-phases of power including first, second, and third phases, a low-pass LCL filter connected to the AC mains, the low-pass LCL filter including at least LCL filter capacitors and downstream LCL filter inductors downstream of the LCL filter capacitors, a first switching device connected between the AC mains and LCL filter, the first switching device configured to disconnect respective ones of the LCL filter capacitors from the AC mains, a second switching device connected between a first node and a second node, the first node connected to one of the LCL filter capacitors associated with the third phase, and the second node connected to the drive rescue battery and one of the downstream LCL filter inductors connected to the third phase, and a frequency converter including a rectifier circuit configured to provide a DC supply voltage, the method comprising:

opening the first switching device and the second switching device to disconnect the LCL filter from the AC mains and form a test load for testing the capacity of the drive rescue battery while disconnecting the one of the LCL filter capacitors associated with the third phase from the test load, the test load including a series connection from one of the downstream LCL filter inductors and the LCL filter capacitors associated with the first phase to one of the LCL filter capacitors and the downstream LCL filter inductors associated with the second phase; and

determining at least one of a voltage or a current of the drive rescue battery resulting from the test load.

2. The method of claim 1 , further comprising:

modulating, e.g. by pulse width modulation, transistors of the rectifier circuit which are connected to the first and second phases to generate an AC-voltage from the DC supply voltage supplied by the drive rescue battery, which AC-voltage is applied to the test load.

3. The method of claim 2 , wherein the modulating comprises:

operating the high side electronically switchable switching means of the rectifier circuit connected to the first phase and the low side electronically switchable switching means of the rectifier circuit connected to the second phase to be closed while operating the other electronically switchable switching means of the rectifier circuit connected to the first and second phases to be open, and

operating the high side electronically switchable switching means of the rectifier circuit connected to the second phase and the low side electronically switchable switching means of the rectifier circuit connected to the first phase to be closed while operating the other electronically switchable switching means of the rectifier circuit connected to the first and second phases to be open.

4. The method of claim 2 , wherein the transistors of the rectifier circuit connected to the first and second phases are modulated such that a fundamental frequency and a voltage level of the AC-voltage over the capacitors of the LCL-filter connected to the first and second phases are controlled to provide a constant discharge power as a reference value, e.g. 200 W, to the drive rescue battery, wherein a discharge value is determined for comparison with the reference value by measuring a voltage and a current of the drive rescue battery.

5. The method of claim 1 , wherein, when the series connection is used as the test load for testing the capacity of the drive rescue battery, the electric motor is at rest.

6. The method of claim 1 , further comprising:

after opening the first switch and prior to opening the second switch to form the test load:

disconnecting an inductor of the LCL-filter connected to the third phase, which inductor is connected downstream of a capacitor of the LCL-filter connected to the third phase, to the third phase of the rectifier circuit, upstream of the inductor from the rest of the LCL-filter; and

connecting one terminal of the drive rescue battery to the inductor of the LCL-filter connected to the third phase such that the inductor forms a boost converter storage choke in the rescue operation mode.

7. The method of claim 6 , wherein a boost converter is formed by a low side transistor of the rectifier circuit connected to the third phase as a boost converter switch, a diode, which is switched in parallel to a high side transistor of the rectifier circuit connected to the third phase, as a boost rectifier, and a capacitive intermediate device of the frequency converter for leveling the DC supply voltage as a boost converter capacitor.

8. The method of claim 6 , wherein either a negative terminal of the drive rescue battery is connected to a DC-link minus potential of the DC supply voltage and a positive terminal of the drive rescue battery is connected to the inductor of the LCL-filter connected to the third phase or the positive terminal of the drive rescue battery is connected to a DC-link plus potential of the DC supply voltage and the negative terminal of the drive rescue battery is connected to the inductor of the LCL-filter connected to the third phase.

9. The method of claim 1 , further comprising:

analyzing results of the testing of the capacity of the drive rescue battery to determine an urgency of performing maintenance on the drive rescue battery.

10. A non-transitory computer readable medium storing a software program that, when executed on a computer, configures the computer to perform the method of claim 1 .

11. The method of claim 1 , wherein

the transportation system is one of an elevator, escalator and a moving sidewalk,

the rectifier circuit is an Active Front End, and

high-side transistors and the low-side transistors included in the rectifier circuit are Insulated Gate Bipolar Transistors (IGBTs).

12. A testing arrangement for testing a capacity of a drive rescue battery configured to drive an electric motor of a transportation system in a rescue operation mode, wherein the testing arrangement comprises:

a detector configured to measure one or more of a voltage and a current of the drive rescue battery;

an AC power supply including AC mains configured to supply three-phases of power including first, second, and third phases;

a low-pass LCL filter connected to the AC mains, the low-pass LCL filter including at least LCL filter capacitors and downstream LCL filter inductors downstream of the LCL filter capacitors;

a first switching device connected between the AC mains and LCL filter, the first switching device configured to disconnect respective ones of the LCL filter capacitors from the AC mains;

a second switching device connected between a first node and a second node, the first node connected to one of the LCL filter capacitors associated with the third phase, and the second node connected to the drive rescue battery and one of the downstream LCL filter inductors connected to the third phase;

a frequency converter including a rectifier circuit configured to provide a DC supply voltage;

and

a switch controller configured to control the first switching device and the second switching device to,

close the first switching device and the second switching device during normal operation to connect the LCL filter to the AC mains to supply power over the first, second, and third phases to the frequency converter to drive the electric motor, and

open the first switching device and the second switching device to disconnect the LCL filter from the AC mains and form a test load for testing the capacity of the drive rescue battery while disconnecting the one of the LCL filter capacitors associated with the third phase from the test load, the test load including a series connection from one of the downstream LCL filter inductors and the LCL filter capacitors associated with the first phase to one of the LCL filter capacitors and the downstream LCL filter inductors associated with the second phase.

13. The testing arrangement of claim 12 , wherein the rectifier circuit includes high-side transistors and low-side transistors, the one of the downstream LCL filter inductors associated with the first phase is connected to a node between a pair of the high-side transistors and the low-side transistors connected to the first phase, and

the one of the downstream LCL filter inductors associated with the second phase is connected to a node between a pair of the high-side transistors and the low-side transistors connected to the second phase.

14. The testing arrangement of claim 12 , further comprising:

a third switching device connected between the drive rescue battery and the second node, wherein

the switch controller is further configured to open the third switching device during the rescue operation mode to disconnect the drive rescue battery from the second node such that the one of LCL filter inductors connected to the third phase forms a boost converter storage choke.

15. The testing arrangement of claim 14 , wherein

the one of the downstream LCL filter inductors associated with the third phase is connected to a node between a pair of the high-side transistors and the low-side transistors connected to the third phase.